The stator or rotor of an electric machine, such as a motor or a generator, is typically fabricated from a soft magnetic material. The soft magnetic material may be provided in the form of laminations cut from a soft magnetic alloy foil which are stacked to form a laminated core. In use in an electric machine, the magnetic flux is carried in the soft magnetic material of the stator or rotor. Generally speaking, the higher the flux density in the material at a given field strength, the less material that is required and the higher the torque that can be achieved. Therefore, the size of the laminated core can be reduced if the magnetic flux carried by the soft magnetic core material is high. However, higher flux densities can lead to increased iron losses which can decrease the efficiency of the electric machine. These losses can be reduced by reducing the thickness of the laminations and/or by suitable selection of the soft magnetic material, for example.
GB 2 484 568 A discloses an electric motor, in which the rotor and/or stator has a soft magnetic laminated core made from laminations having the following composition by weight: 35-50% nickel, 0-2% cobalt, 0-1% manganese, 0-0.5% silicon and at least one of 0.5-8% chromium and/or 0.5-8% molybdenum, wherein the sum of Mo+Cr lies in the range 0.5-8%, with the balance being iron and impurities. This composition of the soft magnetic alloy has a high electrical resistance and low coercive field strength which leads to lower eddy current and hysteresis losses in a laminated core made from laminations of this composition.
However, further improvements for soft magnetic laminated cores are desirable.